NOAA Issues An El Nino Watch, Says There's A 50% Chance For Development Later This Year

Forecast models predict an
increase in sea surface temperature anomalies later this
year.NOAA

On Wednesday, NOAA's Climate Prediction Center issued an El Niño watch, with a roughly
50% chance of development in the summer or fall of this
year.

El Niño, also called the southern oscillation,
is a warming of the tropical Pacific ocean that happens about
every five years. This warming changes wind patterns and affects
weather and storm systems around the world.

On the eastern coast of the United States, for example, strong
El Niño events generally result in warmer, dryer than
average winters. California, on the other hand, could expect a
wetter than normal winter. This could be beneficial for the
currently rain-starved state.

"Increased thunderstorm activity over the eastern Pacific allows
moisture to rise into the upper atmosphere and leak into this
branch of the jet stream," the Washington Post's Dennis Mersereau
explains, "creating the opportunity for beneficial rainfall
across the affected areas next fall and winter, especially in
California where they are experiencing exceptional drought
conditions."

El Niño could also lead to fewer storms
during the Atlantic hurricane season.

"El Niño conditions tend to
make quieter than average Atlantic hurricane seasons, due to an
increase in upper-level winds that create strong wind shear over
the Tropical Atlantic," according to Wunderblog's Jeff Masters.

For an El Niño event to be declared, average sea surface
temperatures in the eastern Pacific need to be 0.5°C above
average or warmer for three months in a row — so there's now a
50% chance these temperature anomalies will happen later this
year.

An animation from NOAA shows weekly average sea surface
temperature anomalies in the tropical Pacific for the past 12
weeks.NOAA

The El Niño watch doesn't necessarily mean that El Niño
will occur. “A watch simply means that conditions across the
tropical Pacific are favorable for the development of El Niño
during the next, roughly, three to six months,” said Mike
Halpert, deputy director of the Climate Prediction Center,
according to Weather.com.

"While all models predict warming in the tropical Pacific, there
is considerable uncertainty as to whether El Niño will develop
during the summer or fall," NOAA said in an alert. "If westerly
winds continue to emerge in the western equatorial Pacific, the
development of El Niño would become more likely. However, the
lower forecast skill during the spring and overall propensity for
cooler conditions over the last decade still justify significant
probabilities for ENSO-neutral."